From prior art sensor devices are known, which may be arranged for example on a hand-held device, in order to detect quantitatively measurement parameters. For example it is known to provide infrared sensors in a mobile phone in the area of the loudspeaker, with which the distance to an object may be detected. So for example it may be detected how far is the mobile phone to an ear. Depending on the distance, the display of the mobile phone may be then switched on or off.
It is disadvantageous in this respect, that the infrared sensors are visible from the outside, because at least the probe must be arranged at the surface of the mobile phone. Thus the possibilities of the design of the mobile phone are limited. Moreover, it cannot be reliably detected, if the mobile phone lies in fact at the ear or if the infrared sensor or the probe is not covered by e.g. a hand.